Adolescents are at high risk for sexually transmitted diseases (STDs), which can have serious consequences for their future health and fertility, and which can increase their vulnerability to HIV infection. Cervical ectopy and use of oral contraceptives (OC), both common in adolescence, are risk factors for chlamydia, the most common inflammatory STD. Standardized, reliable measurements of ectopy have not been employed across studies. The independent risk of OC use stratified by ectopy has not been well studied. The association among Depot Medroxy Progesterone Acetate (DMPA), a contraceptive widely used among adolescents, ectopy and STD acquisition has not been reported. The aims of this proposal are to study prospectively: 1) the natural history of cervical ectopy and the transformation zone (T zone) in sexually active adolescents, 2) the impact of DMPA and a combined estrogen-progestins (OC) over time on cervical ectopy/T zone; 3) the relation between the size of the area of ectopy/T zone and STD acquisition, including chlamydia, gonorrhea, trichomonas and HPV; and 4) the risk of STDs in OC users compared to DMPA users stratified by the extent of cervical ectopy/T zone. Design: This is a 5 year prospective study on 500 inner-city sexually active nonparous females aged 12-18, some of whom will initiate DMPA or OC. They will be recruited consecutively from the Adolescent, Pediatric and community-based OB/Gyn Clinics of the University of Maryland, Baltimore, where the study will be conducted. Participants will be seen every 6 months for medical/sexual history, complete physical and pelvic examinations, and specimen collection of STDs. Cervicography will be used to determine the areas of ectopy and T zone, measured by computerized planimetry. This is an innovative reliable, sensitive and standardized method of measurement. Behavioral data will be collected anonymously by audio assisted computer interview (A-CASI). Interim follow up visits (every 3 months) will include behavioral risk by ACASI, medical history and incidence of STDs by urine screening and from the City STD registry. Summary. This proposal will 1) use a standardized measure of ectopy in young nonparous adolescents before and during hormonal contraceptive use; 2) address the relation between STDs and OCs, especially those OCs containing new progestins; 3) be one of the few studies to examine the association among DMPA, STDs and ectopy in adolescents; 4) recruit a difficult cohort with one of the highest rates of STDs, especially chlamydia infection. The team of researchers has expertise on STDs, adolescent health, and cervical anatomy. They have collaborated on the preliminary study and have experience in planning, implementing and managing successful longitudinal studies on high-risk youth.